Problem: ${4 \div 0.8 = {?}}$
Solution: $ {4 \div 0.8 = 4 \div \dfrac{8}{10}} $ $ {\phantom{4 \div 0.8} = 4 \div \dfrac{4}{5}} $ Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. $ {4 \div \dfrac{4}{5} = 4 \times \dfrac{5}{4}} $ $ {\phantom{4 \div \dfrac{4}{5}} = \dfrac{4 \times 5}{4}} $ $ {\phantom{4 \div \dfrac{4}{5}} = \dfrac{20}{4}} $ $ {\phantom{4 \div \dfrac{4}{5}} = 5} $